/* Persistent navigation for every USBB page. */
.usbb-return-nav{position:fixed;left:20px;bottom:calc(20px + env(safe-area-inset-bottom,0px));z-index:1000;display:flex;gap:8px;padding:8px;border:1px solid rgba(212,175,55,.45);border-radius:12px;background:rgba(13,20,30,.96);box-shadow:0 4px 20px rgba(0,0,0,.3)}
.usbb-return-nav a,.usbb-return-nav button{display:inline-flex;align-items:center;justify-content:center;min-height:44px;padding:8px 14px;border:1px solid #D4AF37;border-radius:7px;background:transparent;color:#E9CB70;font:700 14px/1.4 "Noto Sans TC",sans-serif;text-decoration:none;cursor:pointer}
.usbb-return-nav a:hover,.usbb-return-nav button:hover{background:#D4AF37;color:#121820}
.usbb-return-nav a:focus-visible,.usbb-return-nav button:focus-visible{outline:3px solid #fff;outline-offset:3px}
body{padding-bottom:110px}
@media(max-width:600px){.usbb-return-nav{left:12px;bottom:calc(12px + env(safe-area-inset-bottom,0px));gap:6px;padding:6px}.usbb-return-nav a,.usbb-return-nav button{padding:8px 12px}}